As shown in FIG. 1, a conventional headrest moving device that is used to move a headrest of a vehicle back and forth comprises: a cylindrical rod-shaped moving body 20, with a coil spring 30 wound around the outer circumferential surface of the moving body 20; a first tubular support member 50 in which the first end of the moving body 20 along with the coil spring 30 passes through so as to slide therethrough and which is provided in the sidewall thereof with an insert slit 51 that holds the distal arm of the first end of the coil spring 30 therein, and which surrounds and holds the first end of the coil spring 30 an actuating member 40 that surrounds the second end of the coil spring 30 and is provided with a spacing part 42 in which the distal arm of the second end of the coil spring 30 is inserted so as to be guided by the spacing part 42, with a handle 41 extending from the outer circumferential surface of the actuating member in a radial direction; a second tubular support member 60 that supports the second end of the coil spring 30 in the actuating member 40; and a tubular locking member 10 that surrounds both the actuating member 40 and the first and second support members 50 and 60 so as to hold them, with an axial locking slit 11 formed in the sidewall of the locking member 10 so as to receive the handle 41 of the actuating member 40 therein in such a way that the handle 41 can be rotated in the slit 11.
The actuating member 40 is formed by bending a plate material so that the member 40 can form a tubular body, in which the first end of the plate material forms the spacing part 42 and the second end vertically extends so as to form the handle 41.
The first end of the second support member 60 is configured to form a two-stepped end, the inside end of which abuts on the second end of the actuating member 40.
When assembling the parts into the above-mentioned device for moving the headrest back and forth, the actuating member 40 is combined with the locking member 10 in such a way that the handle 41 of the actuating member 40 is exposed downward to the outside of the locking member 10 through the axial locking slit 11 of the locking member 10. Further, the first end of the coil spring 30 is surrounded and held by the first support member 50, and the second end of the spring 30 is inserted into the actuating member 40, thereby being held in the actuating member 40.
In the above state, the coil spring 30 holds the moving body 20 in a combination of surface contact and point contact, so that the moving body 20 cannot move.
However, when the handle 41 of the actuating member 40 is rotated so as to increase the diameter of the coil spring 30 that holds the moving body 20, the interval between neighboring turns of the coil spring 30 is increased and releases the moving body 20, so that the moving body 20 can slide back and forth in the hollow openings of the first and second support members 50 and 60 without intervening with the coil spring.
However, the conventional device for moving the headrest back and forth is problematic in that, because the headrest is moved back and forth only in response to a movement of the handle, the device is inconvenient to a user.
Further, although a technique in which the handle can be actuated by a wire-operated mechanism instead of a hand-operated mechanism was developed and proposed, the wire-operated mechanism is problematic in that a difference undesirably occurs between operations and the construction becomes complicated, and the production cost increases.